Thermostatic valve for fuel pumps



June 1, 1965 A. c. KORTE 3,186,470

THERMOSTATIC VALVE FOR FUEL PUMPS Filed Dec. 30, 1960 2 Sheets-Sheet l Qa r- Q m I INVENTOR. ALFRED C. KORTE AGENT V 2 Sheets-Sheet 2 INVENTOR.ALFRED C. KORTE BY A GENT June 1, 1965 A; c. KORTE 'THERMOSTATIC VALVEFOR FUEL PUMPS Filed Dec. 30. 1960' FIG.3.

United States Patent O tries, Incorporated, New York, N.Y., acorporation of- New lersey Filed Dec. 3%, 60, Scr. No. 79,753 1 Claim.(6!. 158-353) This invention is directed to .a fuel system andparticularly to a fuel line pressure relief structure for use in a fuelsystem operative with internal combustion engines.

conventionally, a fuel system for an internal combustion engine used,for example in a motor car consists of a source of fuel, such as a fueltank, a carburetor for providing the appropriate emulsification of thefuel and its mixture with air prior to its use in the engine, and apumping means for bringing the fuel from the fuel source to thecarburetor. The urnping means normally is a diaphragmoperated fuel pumpconnected in a fuel line between the fuel tank and the carburetor. Thediaphragm of the fuel pump is operated from a cam on the engine so thatback and forth movement of the diaphragm provides a flow of fuel througha valve inlet and outlet from the fuel tank to the carburetor. Since thefuel pump is placed between the fuel tank and the carburetor the pumpprovides a subatmospheric pressure on the fuel in the line between thetank and the fuel pump and the atmospheric pressure on the surface offuel in the fuel tank forces fuel from the tank to the fuel pump.However, beyond the fuel pump and between the fuel pump and thecarburetor the fuel is moved by positive pressure from the pumpingdiaphragm.

In the design of cars, at the present time, the trend to lower hoodlines and more compactness of the engine and its accessories under thehood, exposes the fuel system to the heat of the engine and ambienttemperatures to a greater degree than was the case in previous years.The fuel in all parts of the fuel system is exposed to high temperaturessuch that there is a great tendency of the fuel to vaporize before itmixes withair in the carburetor. Such vapor conditions in the fuelsystem have been found very detrimental to efficient operation of thefuel pump I in the lines and in the pump allows the pressure of the pumpto be dissipated or absorbed to an extent that only small amounts offuel passalong the fuel line to the carburetor. i e t a Not only is thiscondition of vapor lock accentuated by the high ambient temperatureswhich exist under cer dflhffi'm Patented June 1, i965 "ice if the enginewere running and the car moving. Such a period in which the enginestands or soaks greatly increases the temperature of the fuel in thefuel system.

When a car is slowed down to a stop, the carburetor fuel bowl fills andthe needle valve in the carburetor closes the fuel line from the pump.The pump then builds up the pressure of fuel in the line between thepump and the carburetor to a point where the fuel pressure holds thepump out of operation, since the fuel is pumped by spring action ratherthan a positive action from the pump driving cam of the engine. Thus,upon the stopping of the car, fuel between the carburetor and pump underthe spring pressure of the pump will also be exposed to the ambienttemperatures of a soak period to an extent that the fuel pressure willbuild up and force fuel past the needle valve of the carburetor into thefuel bowl. The added increase in the amount of fuel in the fuel bowlwill permit the fuel to run out through the fuel nozzle into the intakemanifold of the engine and, upon starting the engine, the excessiveamount of fuel in the intake manifold results in a difficult starting ofthe engine.

It is therefore an object of this invention to provide a novel fuelsupply system for an internal combustion engine in which the problem ofvapor lock is minimized.

It is a further object of this invention to provide a novel fuel supplysystem in which the tendency of fuel in the system to vaporize under hotambient conditions is minimized.

It is another object of this invention to provide a novel fuel system inwhich the tendency of vapor lock in the fuel system to reduce theefficiency of the fuel pumping means is minimized.

FIG. 1 is a schematic showing of a fuel system illustrating theinvention and showing a fuel pumping means and a representativecarburetor structure in elevation section.

FIG. 2 is a plan view of the pumping means of FIG. 1, with a portion ofthe inlet housing removed.

FIG. 3 is an enlarged sectional view of the vapor relief control meansin accordance with the invention, and taken on section line 33 of FIG.2.

FIG. 4 is an enlarged view of the spring element of the control means ofFIG. 3.

Referring now to the drawing for a better understanding of theinvention, the fuel system is shown as applied to a conventionalinternal combustion engine E having an intake manifold M. A carburetoris shown at 10 mounted on the engine E and having a fuel and air mixtureconduit 12 with the lower end thereof connected to the inlet of theintake manifold M. The carburetor 19 in turn has a fuel inlet fitting 12connected by a fuel conduit, represented by the dotted line 14, to afuel pump structure 16. The fuel pump 15 has an inlet represented tainoperating conditions, but also, since the fuel in the line between thefuel tank andthe fuel pump is under a subatmospheric pressure, there isadefinitely greater ten dency of the fuel to vaporize. Furthermore, theincrease in the volatility of the fuel components in modern fuels hasaided in the occurrence of this condition of vapor lock.

Besides the harmful elfects of vapor lock on the pump ing efliciency ofthe fuel pump, a vapor lock or vapor condition in the fuel line between.the pump and carburetor is one which provides a difficult ,and'hardstarting of the engine after the engine has undergone a shortperiod ofsoak. Such a conditionsis that in which the engine,

after being what a fast rate for a periodof time during hotweather, isstopped for a few minutes. Since the cooling system of the engineisinoperative, the storedheat in the engine as well as the hot ambientair prevents dissipa 'tion of the heat to the same extent as would be'possible at 15 to which a fuel conduit, represented by the dotted line29, connects the fuel pump 16 to a source of fuel consisting of a fueltank 22.

The details of the carburetor l9 and the fuel pump 16 are somewhatconvention and well known and only those parts of these structures willbe described for the understanding of the invention. a 7

Fuel pump 16 consists of an inlet housing 24 in which there is formedwith a valve housing 33 an inlet chamber .26 and an outlet chamber 28separated by a transverse wall structure 29. The inlet housing 24 andvalve housing 33 are fixed together with a gasket 35 between them byscrews 37. (PIG. 2) extending upwardly from the valve housing33 into theinlet housing 24. Gasket 35 is sealed acrossthe outlet chamber 28 toform an air dome structure as shown in FIG. 1.

- A flexible pumping diaphragm 30 is sealed around its periphery betweena flange portion 32 of the pump body 1 45 and a flange 34of the valvehousing 33. Flanges 32 and 34 are held together by screws 31. To thecenter of pumping diaphragm 30 are mounted backing plates 36 and 38,respectively. To the centers of back plates 36 and 38 and tightlyholding them together with pumping diaphragm 36 in between, is fixed oneend 39 of a metallic stem 40, the other end 41 of which extends througha rubber gasket 42 into contact with a rocker arm 44 pivotally mountedon a rod bearing 46 in the lower portion of pump body 45. An end 48 ofrocker arm 44 is kept in operative contact with one end of a push rod 50mounted for sliding movement in a bearing 51 of engine E. Spring 52between rocker arm 44 and the pump body 45 biases the rocker arm 44 intocontact with rod b, which in turn is oscillated in bearing 51 by virtueof its contact with a rotating cam 54 driven by the engine E.

The function of the rocker arm 44 is to load a spring 56 mounted betweenthe clamping plate 38 and a flanged force diaphragm 3t) upwardly in apumping stroke.

Pumping diaphragm 30 forms with the valve housing 33 a pumping chamber69, which is connected by passages 62 to the inlet chamber 26 and bypassages 64 to the outlet chamber 28, respectively. Closing passages 62is a solid valve washer 66, which is spring-pressed upwardly, as viewedin FIG. 1, against the lower ends of passages 62 to provide an inletvalve to the pumping chamber 6%. In a similar manner a solid valvewasher '70 is springpressed downwardly to close off passages 64 andprovide an outlet valve from the pumping chamber 60.

Upon operation of engine E, rod 50 and rocker arm portion 48 arereciprocally driven by cam 54 upwardly against the bias of spring 52,which in turn drives rod 50 downwardly and rocks arm 44 clockwise as cam54 returns to its low point. The downward movements of rocker arm 44will pull diaphragm 30 downwardly to suck fuel from the fuel line 210and tank 22 into the inlet chamber 25 of the pump 16 and pastvalveod'into the pumping chamber 6%. Each time rocker arm 44 releasesstem 4th, the driving spring 56 forces diaphragm 3t upwardly and drivesfuel out of the pumping chamber 60 past the valve 70 and through thepump outlet 25.

Fuel is thus forced into the carburetor inlet 12 and into a fuel bowl74. A float '75 within fuel bowl 74 is pivotally mounted on a shaft 77and is fixed to a valve operating lever 76 which contacts one end of aneedle valve '78. A pointed head 30 of needle. valve '78 opens andcloses off the fuel passage through'the inlet fitting '12 of thecarburetor. When the level of fuel in bowl 74 reaches the desiredpredetermined amount, lever 76 will press against the needle valve 78 toclose off the inlet passage to the carburetor. With needle valve 78closed,

pump spring 56 will be unable to drive diaphragm 30 in a pumping stroke,and the diaphragm 3t] and rod 40 will be held in a downward position, asviewed in FIG. 1, by the pressure of fuel trapped between valve 66 andvalve 7 8.

The other portions of the carburetor 10 are somewhat conventional andincludes a calibrated orifice or jet structure 82, the passage of fuelthrough which is controlled by a tapered metering rod 84 operated by apiston and cylinder control sensitive to manifold pressure. Fuel passingthrough orifice 82 fills a well structure 86 to the a level of the fuelin bowl '74. Within the mixture conduit of carburetor it there is formeda primary venturi structure 87 and a main venturi 38 to provide a dropin air pressure to feed fuel from bowl 74 into passage 12 for mixturewith air sucked into the manifold M of engine E. Because of the drop inpressure within the primary venturi 87, fuel in bowl 74, underatmospheric pressure, will be forced upwardly through a fuel tube 90into the fuel nozzle 92, at which point fuel will enter the air streampassing into the manifold M. Additional air is mixed with the fuelbefore it leaves fuel nozzle 92 to provide an atomization of the fuelfor optimum mixture with air in the mixture conduit 12.

A manually operated throttle 96 controls the flow of air through passage12, while an unbalanced choke valve d8 pivotally mounted in conduit 12provides for richer mixtures during cold operating conditions and forengine starting.

The operation of the fuel system shown in FIG. 1 is one in which, undercranking or operating conditions, the engine E drives the operating cam54 in a manner described above for the operation of the fuel pump 16.The pumping of fuel from tank 22 into the pump inlet chamber 26 placesthe fuel in the conduit 20 under a subatmospheric condition, while fuelpumped from the pumping chamber 69 into the outlet chamber 28 and intothe fuel line 14 places the fuel under normal pressures greater thanatmospheric and something in the order of 5 to 6 pounds per square inchin a conventionally operating fuel pump. This pressure in fuel line 14drops when the needle valve 78 opens to permit fuel flow into the fueltank 74.

During the operation of the fuel system with an automative vehicle inhot weather, the fuel tank is exposed to the radiated heat from thehighway and to the relatively high ambient air temperature. This causesthe temperature of fuel in the tank 22 to approach that of the ambientair or higher. Furthermore, the mounting of fuel pump 16 on the engine Ewith the fuel lines 20 and 14 adjacent to hot engine parts and alsoexposed to heat radiated from the engine causes the fuel in these linesto reach a higher temperature than that in the tank 22. The increasedvolatility of modern fuels together with these hot ambient conditionsencourages vaporization of the fuel in lines 20 and 14, as well as inthe various cavities of pump 16. Often, under such conditions, thereoccurs a vaporlock condition in which fuel vapors will collect in thefuel lines 20 and 14 and in the various pump cavities to hinder thenormal flow of fuel from tank 22 to the carburetor 10 by action of thepumping of the fuel pump 16. An excessive amount of vapor in theseportions of the fuel system greatly reduces the effectiveness of thepumping action of diaphragm 30 since the fuel vapor merely is compressedby action of the pump with little or no actual pumping of solid fuelthrough the fuel lines. The fuel in line 20 under a sub-atmosphericpressure will also tend to vaporbe under pressure as the fuel bowl willnormally be filled and needle valve 78 closed. The pressure of the fuelin line 14 may also be increased by the bias of spring 56, if the driverod 50 stops on a low position of cam 54. The conditions then are suchthat heat radiated and conducted from the engine as Well as the ambientair temperature magnified by low hood lines will cause fuel in line 14to increase in temperature and to the vaporization point. Valves 70 and66 prevent the fuel from draining back through fuel line 29 into thetank 22, while closure of needle valve 78 prevents fuel and vapor frompassing into the fuel bowl 74. However, as the pressure in line 14builds up to an abnormal condition, fuel 'willbe forced past the needlevalve 78 into the fuel bo'wl 74 to' cause an overflow of bowl 74 out ofthe nozzle 92. This action dumps a quantity of raw fuel into the intakemanifold M and prevents an easy starting condition when the engine iscranked.

The build-up of vapor in line 14 will reduce the. efficiency of thepumping action of the fuel pump 16, as the vapor pockets in line 14 andin the outlet chamber 28 will absorb the fuel pressure exerted bypumping diaphragm 30 and will decrease the effective flow of pumped fuelto the carburetor 10. Furthermore, conditions in line 20 during a hotsoak or during abnormally hot operating conditions and are such that thefuel, under sub-atmospheric pressure in line 20, readily vaporizesforming a foaming consistency of the fuel entering the inlet chamber 26of the pump. The pump then merely pushes along a foamy mixture of fueland vapor in which the amount of solid fuel is small, and under someconditions insuflicient to operate the engine E. As the vapors build upin the pumping chamber 60, the pump takes longer and longer strokesbecause little fuel passes into the fuel bowl 74 and the float 75 staysdown and allows the needle valve 78 to remain open. This drops thepressure in the pump chamber 60 and the outlet chamber 28 to reduce theefiectiveness and efficiency of the pump.

In accordance with the invention, means are provided in the conduit frompumping chamber 60 to the carburetor to correct and prevent theconditions of vapor lock or vapor accumulation in the fuel system. Sucha device is disclosed in FIG. 2 and an enlarged showing is in FIG. 3.The invention is in the provision of an outlet passage 100 from theoutlet chamber 28 of the pump, which passage 100 is connected by a fuelconduit line 102 to permit the flow of fuel from pumping chamber 28 in areturn path to the tank 22. The passage 100 is fitted with a nipple 104,to which the conduit 102 is attached. Threaded into the outlet passage100 is a valve seat structure 106 (FIG. 3) into which is fitted acalibrated orifice structure 108 to provide a predetermined flow of fuelinto the conduit 102. The orifice structure 108 is partially closed by avalve device consisting of a valve element 110 formed by an enlargedhead of a valve rod 112 slidably mounted in abearing portion 114 of thevalve seat structure 106. Fitted to a threaded end portion 116 of rod112 is a shaped nut 118 having a peripheral groove 120 extending aroundits outer surface. The bearing portion 114 of the valve seat structure106 also is formed with a circumferential groove 122 extending aroundits outer surface. A thermostatic spring 124 is coaxially mounted on rod112 between the nut 118 and the bearing portion 114 of the valve seatstructure 106. Spring 124 is a double wound helix formed of bimetallicspring material.

FIG. 4 shows spring 124 in an enlarged view. Spring 124 is formed of athin bimetallic strip which is formed in a long helix and, then in turn,the helix is wound into a coil to form the convolutions of the spring.Each end of the bimetallic strip is formed into a shaped hook structure130 which is fitted into one of the peripheral grooves 120 and 122,respectively. The valve head 110 is thus biased against a seat formed inthe opening of orifice structure 108 by the spring 124 between the fixedbearing element 114 and the nut 118 on rod 112. Adjustment of the nut118 will provide the desired biasing pressure of the valve head 110against the valve seat 108. The bimetallic properties of the springenable it to ex pand as the temperature of the fuel to which it isexposed in chamber 26 rises. Expansion of the spring 124 releases itsbiasing force on valve head 110. Further increase in fuel temperaturewill cause additional expansion of spring 124 to lift valve head 110away from the valve seat of orifice 168. Valve head 110 has a smallgroove 126 in its surface to form a constant bleed from chamber 28 intothe return fuel conduit 102.

The operation of the device is such that under normal temperatures ofthe fuel in chamber 28 to which the thermostatic spring 124 is exposed,spring 124 will normally bias the valve head 110 onto the seat ororifice 108 and retain operation of the constant bleed 126 only.Furthermore, the normal operating pressure of fuel in chamber 26 in theorder of 5 to 6 pounds per square inch, aids in holding the valve 110against its seat as well. This constant bleed 126, under normalconditions, has the effect of preventing any build-up of vapor in theoutlet chamber 28. However, as the conditions for vapor lock occur, thefuel and vapor mixture within the pump takes on a frothy consistency andthe mixture becomes heated because of the adverse operating conditions.temperature of the fuel rises in the outlet chamber 28 of the pump, thespring 124 will tend to expand to first relieve its biasing pressure onthe valve 110 and then to overcome the pressure of the fuel itselftending to hold the valve 110 against its seat. As the valve 110 movesaway from its seat, the passage of fuel into the return line 102 isincreased and it has been found that the fuel vapor escapes throughreturn line 102 more readily than the solid fuel itself. Thus duringpump operation, opening of the by-pass under abnormally hot conditionswill eliminate vapors in the pump and permit a greater flow of solidfuel through the pump, which in turn clears out other vapors trapped inthe various chambers of the pump. Larger quantities of solid fuel, whichcan now pass through the pump, exert a cooling action on the pump itselfand retains this portion of the system at lower operating temperatures.

The device, thus described, forms a thermostatically controlled reliefvalve in which the valve is controlled by a thermostatic heat-responsivespring exposed to the temperature of the fuel in the output portion ofthe pump. The device is one which provides a large by-pass of vaporsback to the tank when it is needed under adverse conditions of hightemperature. During the shutdown of the engine and under hot soakconditions, the constant bleed 126 will also correct the build-up ofpressure in line 14 between the pump and the carburetor to preventflooding of the carburetor fuel bowl. This bleed thus provides a reliefof line 14 back to the fuel tank, since under such conditions the valve70 in the pump is closed.

Under one condition of operation, the spring 124 was adjusted to openvalve 110 at approximately 115 F. when the fuel pressure within chamber28 was around 5 to 6 pounds per square inch. At this temperature andpressure, the fuel has various light ends which will vaporize to a greatextent above F. At the predetermined temperature above 100 F., thethermostatic spring 124 will open and by-pass fuel vapor back to thetank 22.

The opening of valve will take place at different temperatures inaccordance with changes in the pressure of the fuel in the outletchamber 28. As described above, the fuel pressure within chamber 28exerts a closing force on the valve 110, which has to be counteracted byexpansion of a thermostatic spring 124 to open valve 110. Under adverseconditions of high temperature operation, the presence of vapor in theoutlet chamber 28 of the pump causes the pump pressure in chamber 28 todrop. This drop in fuel pressure reduces the closing force of the fuelon valve 110 and permits its opening by spring 124 at a lowertemperature.

I The bleeding of fuel vapor through the fixed bleed 126 or through theopen valve 110 contributes to a greater efficiency of pump operation asthe output pressure in chamber 28 is prevented from building up toproduce a back pressure against the pumping stroke of diaphragm 30.

-I claim:

A fuel system for an internal combustion engine, said system comprisinga source of fuel, a carburetor, a fuel conduit means connecting thesource of fuel and the carburetor, fuel pumping means including adiaphragm pump for delivering fuel from said source to said carburetorforming a part of said fuel conduit means, a return fuel As theReferences Cited by the Examiner UNITED STATES PATENTS 886,945 5/08Clarke 236-93 X 1,251,112 12/17 Rutz 158- 115 1,486,817 3/24 Wartenberg23 693 1,625,964 4/27 Spahr 158115 E Moore ...1 23693 X Gehrig 158-115Peo 236-93 X Peo 2 36-93 'Ebel et a1 15836.3 X Chace et a1 23693 XDonnell 158-363 Gelmer 158 36.4 X B-rohl 15836 Capeh-art 15836.3 Bowers158-363 X FOREIGN PATENTS Germany.

15 JAMES W. WESTHAVER, Primary Examiner. FREDERICK L. MATTESON, JR.,Examiner.

